Long-Chain Gemini Surfactant-Assisted Blade Coating Enables Large-Area Carbon-Based Perovskite Solar Modules with Record Performance

Highlights Trace amounts of long-chain gemini surfactants are essential for blade-coating of high-quality perovskite films, enabling a 17.05% efficient full printed carbon-based module (50 cm2 active area). Only when the surfactant chain is over a critical length will the gemini surfactant be effective for blade-coating of perovskite films. The surfactants increase the capillary number of perovskite precursor solution, reduce the local disturbance and combat inhomogeneous solidification during blade coating, thus allowing high-quality perovskite films to be formed. Supplementary Information The online version contains supplementary material available at 10.1007/s40820-023-01155-w.

The bulk MAPbI3 with the space group PNMA (a = 8.56 Å, b = 9.25 Å, c = 12.96 Å,  =  =  = 90  ) is cleaved along the (0 0 -1) plane with I as termination. A 20 Å vacuum layer was added to separate the interaction between periodic images. Then, we expand it as 1  2  1 supercell (MAPbI3 (0 0 -1)). The 1/3 of MA molecules in MAPbI3 (0 0 -1) is replaced by the FA molecules to construct the MA0.65FA0.35PbI3 (0 0 -1). For investigation of I vacancy defect, we delete a I atom on the termination of MA0.65FA0.35PbI3 (0 0 -1) to construct a I vacancy VI. The DSPC molecule is too large for DFT calculation, so we choose the group in DSPC molecule which has the defect passivation function for calculation. The defect passivation group of DSPC molecule is added on the VI site of MA0.65FA0.35PbI3 (0 0 -1) to construct VI-DSPC. For investigation of A site vacancy defect, we delete a MA atom on the termination of MA0.65FA0.35PbI3 (0 0 -1) to construct the A site vacancy VA. The defect passivation group of DSPC molecule is added on the VA site of MA0.65FA0.35PbI3 (0 0 -1) to construct VA-DSPC.
Chemical state and qualitative analysis of perovskite surface elements were measured by X-ray photoelectron spectroscopy (XPS, Thermo Fisher ESCALAB 250Xi). Temperature dependent admittance spectroscopy (TAS) was measured on Zahner electrochemical workstation in the dark at various temperatures (T = 280-380 K) controlled by a liquid nitrogen cryostat (Oxford Instruments, OptistatDN). External quantum efficiencies (EQE) were measured by a Zolix detector responsivity measurement system calibrated by a standard silicon cell. Space-charge limited current (SCLC) data were collected by measuring the dark I-V curve on a Zahner Zennium electrochemical workstation. Current-voltage (J-V) characteristics of devices were recorded by a Keithley 2400 source meter under 1 Sun (AM 1.5 G, 100 mW cm -2 , the light intensity was calibrated using a certified standard silicon cell) illumination with a solar simulator (Newport, Oriel Sol3A).

S1.3 Analysis of In-situ Optical Microscope
The in-situ optical microscope images were observed by a polarizing microscope (Shanghai Bimu Instrument, XPY-800E), and the automatic exposure high-speed camera (TOUPCAM, UCMOS05100KPA) was used to capture the images and shoot videos of the whole process. The optical microscope videos were shot under the flowing conditions. The liquid pre-PVK film was bladed at room temperature, and then put on a hotplate at room temperature. The temperature was set as room temperature and slowly raised to 120 o C at a constant rate. The transformation from liquid film to perovskite film was slower than the direct annealing at 120 o C, which was easy to record the transformation process.

S1.4 Analysis of Quartz Crystal Microbalance with Dissipation (QCM-D)
QCM-D can be used to characterize soft materials at the molecular level, in which dissipation (damping) is determined by the stop time of the oscillation after the power disconnecting. Structural properties of film are measured by changes of dissipation at different frequency multiplications. By tracking changes of frequency and dissipation, the viscoelastic information of soft film can be obtained, which is suitable for a wide range of rheological and phase transition applications. Processes such as crosslinking, swelling, entanglement, aggregation, and other conformational changes can be tracked in real time by monitoring viscoelastic changes. In this work, QCM-D data of pre-PVK ink film was measured and fitted respectively by the instrument of QSense Explorer and the software of QSense Dfind (Biolin Scientific Co., Ltd.). 1uL pre-PVK ink spread on the gold electrode as the testing film of pre-PVK ink, then the electrode was placed into the testing chamber. 500 uL/min air blow into the chamber to promote the volatilization of solvent and solidification of the pre-PVK ink film. Thus the raw data that the frequency and dissipation changed with time at different frequency multiplication were acquired. The raw data were fitted by the Broadfit model of QSense Dfind. Therefore, the changes of viscoelasticity were obtained and plotted in Figure S5, in which Δviscosity and Δelastic modulus denoted the relative values between the detectable viscoelasticity in the real-time liquid and the reference viscoelasticity in the initial bulk liquid. The changes of viscosity reflected changes of the proportion of colloidal solids and the degree of interlacement. The changes of elastic modulus reflected the degree of solidification. When bulk liquid began to transform into rigid film through the volatilization of solvent and the crystallization of intermediate phases, the values of Δviscosity and Δelastic modulus had a sudden increase (the steep curve from 1 to 2 and the time of the highest point shown in Figure S5). When the bulk film approached the state of rigid film, the frequency of bulk film was out of the detection range, so the record of solidification process discontinued and the instrument turned to record the unsolidified ink which had similar testing frequency to the reference ink. The solutes of unsolidified ink were further consumed during the process of aging or growth until the solvent was completely removed (the decline curve from 3 to 4 in Figure S5). Due to the negative Δelastic modulus cannot be calculated by the fitting software, the decline trends were symbolized by the arrows below 0 in Figure S5 and Figure S6.

S1.5 Analysis of Time-Resolved Photoluminescence (TRPL)
The TRPL decay curves were fitted to a biexponential rate law: where A1 and A2 are the relative amplitudes, and 1 and 2 are the lifetimes for the fast and slow decays, respectively.

S1.6 Analysis of Space-Charge-Limited Current (SCLC)
The trap-filled limit voltage was determined by the trap density (Nt): where VTFL is the trap filled limit voltage, e is the elementary charge, L is the thickness of perovskite, r is the relative dielectric constant of perovskite, and 0 is the vacuum permittivity.

S1.7 Analysis of Temperature Dependent Admittance Spectroscopy (TAS)
The capacitance spectra was measured from 280 to 380 K in 10 K increments in the dark from 10 2 to 10 5 Hz. An AC voltage of 5 mV was used as an excitation signal and DC bias was kept at 0 V during the measurement. The trap energy level ( а ) was determined by the equation.
where 0 is the characteristic transition frequency, is a temperature-independent Nano-Micro Letters S4/S14 parameter, is the Boltzmann's constant, and is the temperature, respectively. The trap density ( ) can be derived according to the following equation.
( ) = − bi (S4) where bi is the built-in potential, is the elementary charge, is the depletion width, is the capacitance, is the applied frequency, respectively. The values of bi and could be obtained from the Mott-Schottky analysis. The demarcation energy ( ) was obtained from the equation.

= ln
where is the capture coefficient for the charge carriers, and is the effective density of states in a given band in the devices, respectively.    The difference values of a) viscosity and b) elastic modulus relative to the reference values of bulk inks. The black arrows (the process from 1 to 2) denote the changes from liquid bulk ink to solid bulk film, and the red arrows (the process from 3 to 4) denote the changes from unsolidified ink to residual solution. The time values are taken from the highest point of 1 to 2 that is detectable by QCM-D. Since the curves below the reference values cannot be obtained by calculation, they are taken to have 0 value, for example, the elastic modulus curves from 3 to 4 in DLPC-and DSPC-pre-PVK ink. According to the results of XRD in Fig. 1c and QCM-D in Fig. S5, the formation of MA2Pb3I8•2DMSO is promoted by the polar head of DSPC Likewise, the black arrows (the process from 1 to 2) denote the changes from bulk ink to bulk film, the red arrows (the process from 3 to 4) denote the changes from unsolidified ink to residual solution. Since the curves below the reference values cannot be obtained by calculation, they are taken to have 0 value, for example, the elastic modulus curves from 3 to 4 in DSPC-(a) and DLPC-pre-PVK (b) inks